Die casting is a manufacturing process for producing accurately dimensioned, sharply defined, smooth or textured-surface metal parts. A steel mold capable of producing tens of thousands of castings in rapid succession is made in at least two sections to permit removal of castings. These sections are mounted securely in a machine and are arranged so that one is stationary (fixed die half) while the other is moveable (injector die half). To begin the casting cycle, the die cavity is coated with a lubricant or mold release material. Then, the two die halves are clamped tightly together by the die casting machine. Molten metal is injected into the die cavity where it solidifies quickly. The die halves are drawn apart and the casting is ejected.
Die casting cycle times vary from less than one second for small components weighing less than one ounce, to thirty seconds or more for a casting of several pounds or more. Dies are filled quickly (normally between five and forty milliseconds) and metal is injected at high pressures (1,500 to over 4,500 psi). Nevertheless, modern automation technology gives close control over these values, thus producing castings with fine detail, close tolerances and high strength.
The die casting process has been automated to improve quality control, speed and safety. For example, safety interlocks prevent filling a mold with a shot of molten metal unless the mold is securely clamped shut and an outer door of a system enclosure is closed to protect the system operator. When a mold is opened after a casting cycle and the finished part is removed, an automated reciprocating sprayer or reciprocator may move down between the open die halves to spray on a lubricant on the die cavity. As the reciprocator returns to its rest position, it blows high pressure air on the mold cavity to remove excess lubricant and dry the cavity faces. The reciprocator is typically activated by the operator after opening the safety door to remove the finished die casting. Regulations have been proposed to require a safety door interlock with the reciprocator to insure that the reciprocator cannot move down when the door is open because the operator may still be in the casting enclosure. However, such an interlock arrangement would add a significant amount of time to the casting cycle time, thereby reducing the productivity of the die casting system.